Centrifugal switch



June 16, 1931. J. F. ADAMS ET AL 1,809,316

CENTRIFUGAL SWITCH I Filed Dec. 1:5, 1927 2 Sheets-Sheet 1 Q A INVENTORS: WITMSSES' ,filznflazwzb Ada-maij71amas 714 11011,

d ATTORNEY June 16, 1931. r J. F. ADAMS ET AL 1,309,816

' CENTRIFUGAL SWITCH INVENTOR-S; mr/vrssns. ,fiiznjfamisz dw d ,ATTORNEYY I mama June 1e, 1931 UNITED) STATES PA ENT OFFICE :romr rumors mans Annrnoms r. ALLEN, or rnrnannnrnm, rmmsnvmm, assrenons 'ro snn'rmr sunry con'rnor. CORPORATION, or rnrmnanrnu, 2mm- SYLVANIA, A coaromrron or rmmsrnvanm 1 CENTRIFUGAL SWITCH Application filed December 13, 1927. Serial No. 239,622.

This invention relates to safety appliances for motion picture projectingmachines.

The invention relates particularly to mechanism which, when the film feeding mechanism falls below a given'speed or stops entirely, willoperate to intercept or cut off the light rays from the film and stop the motor which operates the film feedin mechanism.

This present invention has to 0 articularly with a switch for operating the a ove mechanism.

The ob'ect of the invention is to lprovide an improve switch for operating sa ety appliances for motion picture projecting machines.

Another object is to provide a switch which will be positive in its action and which will eliminate objectionable features in the present switches designed to accomplish this purose.,

:0 p Another object is to provide a switch mechanism which is simple in construction, which has few parts, and which may beeconomical= ly manufactured and assembled.

Safety a pliances of the type which the switch of t is invention is designed to operate. are shown and described in our co-pending application, Serial No. 221,491, filed Septem er 23, 1927.

The invention herein contained is an improvement over the'switch shown and de scribed in our co-pending application, Serial No. 223,306, filed October 1, 1927.

According to this invention the switch, which is of the centrifugal type, is adapted to be operated by a rotating part preferably of the film feeding mechanism, of the projecting machine and. is provided with contactors and which when the mechanism and switch are operated at a predetermined speed are held outward centrifugally, but when the said mechanism and switch fall below the required speed, are swung inward and make contactwith contact rings which break the motor circuit, and stop and intercept'the light rays from the film.

The drawings illustrated an embodimentof the invention and the views therein are as follows: Figure 1 is a fragmentary front view of a projecting machine showing the improved switch applied thereto.

- Figure 2 is a horizontal section through the switch and its operating means and is taken on the line 2'2 of Figure 1 Figure 3 is a vertical section ofthe switch showing one manner of mountin the same,

Figure 4 is a vertical section 0 the entire switch and the line 4-4 of Figure 3 illustrates the point at which the section istaken,

Figure 5 is alike section and the line 5--5 of Figure 3 will serve to illustrate the point at which this section is taken.

In the drawings, like parts are indicated by like reference characters in each figure,

The switch is housed in the casing 11 formed of bakelite or other non-conducting material and has a shaft 12 mounted in a bearing in the end wall 13 of the same. The switch casing is circular and the operating 7. parts are all mounted on the shaft and rotate thereon. a I

- in ractice, the switch is operated from one o the rotating parts of the. projecting machine and it is here shown as operated by the shutter shaft upon which there is mounted a pinion 14 which is fixedly secured thereto by means of a set screw 16. This pinion meshes at all times with the gear 17, mounted on a metallic sleeve 18 which rotates on the so shaft 12 and said sleeve is located near the outer end of said shaft. The casing ,is recessed, as at 20, to permit the meshing of the gear 17 and pinion 14. Both the pinion 14 and gear 17 may be made of graphite impregnated bakelite, fibre or other noiseless and self-oiling material.

The gear is securely fixed to the sleeve 18 which is rotatably mounted on the shaft and held thereon by means of a nut or collar 19. The gear 17 is secured to a circular body 21 by screws 22 and this body, as well as an insulating disk 23, are mounted on the sleeve 18 and rotate therewith. The circular body v21 is preferably formed of bakelite and the sleeve 95 18 may be cast into the same so that the parts may beassembled as a 'unit. The insulating bd y 21 may also have a series of threaded ferrules 24 cast therein and an annular con tactring 26 is held against the face of'said 100 body by screws 27 passing through the same and into two of said threaded ferrules. The contact ring 26 has two contact arms 28 pivotally connected thereto at points diametrically opposite to each other and are mounted on osts fastened intothe contact ring and hel thereon by nuts.

These arms each have an upstanding lug 31 to which one end of a leaf spring 32 is secure ly fastened, and the other end of said spring is free and bears against an eccentric. 33 which is carried by a screw 34 extending into one of the threaded ferrules 24.

Between the contact ring 26 and eccentric 33 a sleeve 36 surrounds the screw 34 in order to elevate the eccentric into a position in line with the free end of spring 32.

A sleeve 37 if insulating material is forced onto the shaft 12 and is positioned between the inner end of the sleeve 18 and the end wall 13 of the casing, and said sleeve has an annular flange 38 on each side of which are circu lar contacts 39 and 41. The flange38 is provided with a pair of hollow lugs 42 which extend from the rear thereof and over which the contact plate 41 fits b holes extending through the same and insu ating washers are place over the lugs and screws 43 extend into the same and connect the said contact plates to ether.

e contact arms 28 are so mounted on the contact ring 26 that the heavy free end of one of the same will engage the contact plate 39 and the free end of the other will enga e the contact plate 41 when the shaft 12 is i 1e or when it has not reached a predetermined speed.

These arms are adapted to be centrifugally operated so that, upon the rotation of said shaft, at the desired speed, the heavy free ends thereof will be thrown outward and break the contact with their respective contact plates. The lugs 31 will act as limiting members or'stops to limit the outward movement of the free ends of the contact arms 28.

' The speed at which this break will occur is regulated by means of the eccentrics 33 which hy loosening the screw 34 may be rotated to increase or 32 and the eccentrics may be set at any desired point by tightening the screw 34.

One of the screws 43 is provided with a terminal 44 to which the wire 45 is connected, thereby making electrical connection with the contact plate 39, while the contact plate 41 is also rovided with a terminal 46 which is held y a screw passing into said ring. This terminal is connected to a wire 47. These wires are carried out through a. hole 48 in the end wall 13 of the casing and are connected into the circuit, as shown in Figure 6. If desired the wires may be tied or otherwise fastoned to the sleeve 37 which insulates the same from the shaft 12.

The end of the shaft'12 is secured in a bracket 49 which is mounted at a convenient place on the projecting machine and the shaft 12 is held against rotation by a set screw 51.

Of course, the switch illustrated may be modified in many ways Without departing from the invention herein set forth and hereafter claimed.

We claim y A centrifugal switch comprising a rotatable pait, means for operatively connecting said part with a moving part of a machine, a rotatable contact ring, contacts havin one end pivotally connected to said ring an electrically connected therewith, leaf springs engaging said contacts and urging the free end thereof inward, stationary contact plates adapted to be engaged by said pivotal contact through the urge of said springs, and eccentrio means for adjusting the tension on said leaf springs to regulate the speed at which the pivotal contacts will be thrown outward- '1 to disengagethe contact plates.

In testimony whereof we have signed our names to this specification.

' JOHN FRANCIS ADAMS.

THOMAS T. ALLEN.

ecrease the tension on the spring 

